Reflection type semiconductor display device

ABSTRACT

A reflection type semiconductor display device which can make satisfactory display even when external light is not satisfactorily intense is provided. A reflection type semiconductor display device according to the present invention can take in light other than incident light on a liquid crystal panel to be an auxiliary light source using optical fibers, and thus, display of high quality level can be made even indoors or in a place where light is faint. Further, by combining the semiconductor display device with a front light, insufficient amount of light can be supplemented with the front light.

This application is a continuation of U.S. application Ser. No.10/895,009 filed Jul. 20, 2004 now U.S. Pat. No. 6,999,137 which is acontinuation of prior U.S. application Ser. No. 10/127,854 filed on Apr.23, 2002 (now U.S. Pat. No. 6,784,952 issued Aug. 31, 2004) which is acontinuation of prior U.S. application Ser. No. 09/407,796 filed on Sep.29, 1999 (now U.S. Pat. No. 6,407,785 issued Jun. 18, 2002).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reflection type semiconductor displaydevice of a direct viewing type, and more particularly, to a reflectiontype liquid crystal display device (liquid crystal panel). The presentinvention also relates to a semiconductor device with a reflection typeliquid crystal display device mounted thereon.

A semiconductor device as referred to in the present invention may be,for example, information processing equipment such as a notebook-sizedpersonal computer, a lap top type personal computer, an electronicnotebook, or a mobile computer, a video camera, a digital still camera,a car navigation system, or a cellular telephone.

2. Description of the Related Art

Recently, an intensive study and development have been carried out withregard to manufacturing technology of liquid crystal panels to make itpossible to provide liquid crystal panels at a relatively low cost.Further, as the information society where Internet, electronic mail, andthe like are utilized has been developed, notebook-sized personalcomputers (hereinafter abbreviated as notebook-sized PCs) have rapidlybecome more popular.

With regard to digital still cameras and video cameras, as they havebeen allowed to have liquid crystal panels mounted thereon such thatimages taken can be viewed on the spot, they have become widely acceptedby consumers.

Liquid crystal panels fall into transmission type ones and reflectiontype ones. In a transmission type liquid crystal panel, illuminationlight is transmitted through the liquid crystal panel from a back lightprovided at the back so that the user can visually confirm the display.On the other hand, a reflection type liquid crystal panel does not needa back light, and the display can be seen through reflection of externallight on the liquid crystal panel. Such a back light consumes about 90%of power consumption of the transmission type liquid crystal panel, andthus, power consumption of a transmission type liquid crystal panel islarge. On the other hand, though the display quality level of areflection type liquid crystal panel is inferior to that of atransmission type liquid crystal panel, power consumption of areflection type liquid crystal panel is smaller than that of atransmission type liquid crystal panel, and thus, a reflection typeliquid crystal panel is advantageous when used in a notebook-sized PC ora mobile PC.

One reason of the inferiority of the display quality level of areflection type liquid crystal panel to that of a transmission typeliquid crystal panel could be the insufficient amount of light when itis used indoors.

These days, in order to solve the problem of the insufficient amount oflight, a technique to provide a reflection type liquid crystal panelwith a front light is adopted to supplement insufficient amount of lightwhen it is used indoors. However, in this case, since a fluorescent lampsimilar to that used as a back light of a transmission type liquidcrystal panel is used as the front light, leading to larger powerconsumption, the advantage of a reflection type liquid crystal panelcannot be obtained.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made in view of the aboveproblem, and an object of the invention is to provide a reflection typesemiconductor display device having high display quality level withoutinsufficiency of the amount of light even when it is used indoors.

In order to solve the above problem, according to the present invention,light other than incident light on a liquid crystal panel is utilized asan auxiliary light source of a reflection type semiconductor displaydevice.

FIG. 1 shows a schematic structural view of a reflection typesemiconductor display device using a reflection type liquid crystalpanel according to the present invention. Reference numerals 101, 102,and 103 denote a main body, a reflection type is liquid crystal panel,and an optical fiber array, respectively. The optical fiber array 103includes a plurality of optical fiber cables 104. Each of the opticalfiber cables 104 is a bundle of a plurality of optical fibers, examplesthereof being shown in FIGS. 2A and 2B. The optical fiber array is usedas means for taking in external light.

In FIGS. 2A and 2B, reference numeral 201 denotes an optical fiber, anenlargement thereof being shown at the lower portion in FIGS. 2A and 2B.The optical fiber 201 has a core and a clad. The index of refraction ofthe core is larger than that of the clad, and light travels as itrepeats total internal reflections at the interface between the core andthe clad. A coating 202 is formed of a resin or the like. A reinforcingmaterial 203 is formed of a resin or the like.

It is to be noted that, in the optical fiber cable 104 shown in FIG. 2A,a bundle of tightly packed optical fibers is covered with the coating202. Further, in the optical fiber cable 104 shown in FIG. 2B, thereinforcing material 203 fills the space among the optical fibers toimprove the strength.

Next, reference is made to FIG. 3. FIG. 3 shows a sectional view of areflection type liquid crystal panel according to the present invention.Reference numeral 301 denotes a substrate. Reference numerals 302 and303 denote driver TFTs (thin film transistors). Reference numerals 304,305, 306, and 307 denote a pixel TFT, a reflection electrode, liquidcrystal, and a counter substrate, respectively. It is to be noted thatthe pixel TFT can be made of amorphous semiconductor film orpolycrystalline semiconductor film. Also it is to be noted that atransparent electrode (not shown) is provided under the countersubstrate.

The optical fiber cables 104 are positioned such that light taken infrom one end of each of the optical fiber cables 104 is emitted from theother end thereof to the counter substrate. Consequently, incident lightentered into the optical fiber cables travels through the opticalfibers, enters the counter substrate 307, traveling through the countersubstrate 307, and then enters the liquid crystal. It is to be notedthat the upper surface of the counter substrate 307 is appropriatelyprocessed to allow incident light on the liquid crystal by eliminatingthe requirement for the total internal reflections of light travelingthrough the substrate at the interface. The processing condition can bemost suitably set through simulation or the like. In FIG. 3, the uppersurface of the counter substrate 307 is formed with patterns, but thepresent invention is not limited thereto.

Alternatively, as shown in FIG. 4, the panel may be structured to use acounter substrate used in a general reflection type liquid crystal paneland a light guide plate 408. Reference numeral 401 denotes a substrate.Reference numerals 402 and 403 denote driver TFTs. Reference numerals404, 405, 406, and 407 denote a pixel TFT, a reflection electrode,liquid crystal, and a counter substrate, respectively. In this case, theupper surface of the light guide plate 408 is processed so as toeliminate the requirement for the total internal reflections of incidentlight traveling through the light guide plate 408 at the interface.

It is to be noted that any suitable means may be used to allow incidentlight taken in by the optical fiber cables 104 to travel through thecounter substrate or the light guide plate into the liquid crystal.

The present invention will be described in view of the structure.

According to the present invention, there is provided a reflection typesemiconductor display device in which light emitted from one end of anoptical fiber enters said reflection type semiconductor display device,wherein the light is external light taken in from the other end of theoptical fiber.

Further, according to the present invention, there is provided areflection type semiconductor display device in which light emitted fromone end of an optical fiber enters a counter substrate of saidreflection type semiconductor display device, wherein the light isexternal light taken in from the other end of the optical fiber.

Still further, according to the present invention, there is provided areflection type semiconductor display device in which light emitted fromone end of an optical fiber enters a light guide plate provided so as tooppose to said reflection type semiconductor display device, wherein thelight is external light taken in from the other end of the opticalfiber.

Preferably, a reflection type semiconductor display device in theforegoing structure further comprises a microlens.

Preferably, a reflection type semiconductor display device in theforegoing structure further comprises a front light.

Preferably, the above-described front light comprises an LED.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic structural view of a reflection type semiconductordisplay device according to the present invention;

FIGS. 2A and 2B show examples of an optical fiber cable;

FIG. 3 is a sectional view of a reflection type liquid crystal panelaccording to the present invention;

FIG. 4 is a sectional view of a reflection type liquid crystal panelaccording to the present invention;

FIG. 5 is a schematic structural view of a notebook-sized PC with areflection type liquid crystal panel according to the present inventionmounted thereon;

FIG. 6 is a sectional view of a reflection type liquid crystal panelaccording to the present invention;

FIG. 7 is a sectional view of a reflection type liquid crystal panelaccording to the present invention;

FIG. 8 shows an optical fiber cable;

FIG. 9 shows an optical fiber and a microlens;

FIG. 10 shows an optical fiber array and a microlens array;

FIG. 11 shows an optical fiber cable;

FIG. 12 shows an optical fiber and a microlens;

FIG. 13 is a schematic structural view of a reflection typesemiconductor display device according to the present invention;

FIG. 14 is a sectional view of a reflection type liquid crystal panelaccording to the present invention;

FIG. 15 shows LEDs used in a front light;

FIGS. 16A to 16C show examples of a semiconductor device with areflection type liquid crystal panel according to the present inventionmounted thereon; and

FIGS. 17A to 17E show further examples of a semiconductor device with areflection type liquid crystal panel according to the present inventionmounted thereon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described in the following. Itis to be noted that the present invention is not limited to thefollowing embodiments.

[Embodiment 1]

The present embodiment is a case where a liquid crystal panel accordingto the present invention is mounted on a notebook-sized PC.

Reference is made to FIG. 5, which shows the appearance of thenotebook-sized PC of the present embodiment. Reference numerals 501,502, 503, 504, and 505 denote a main body, a keyboard, a pointingdevice, a reflection type liquid crystal panel, and an optical fiberarray, respectively.

The optical fiber array of the present embodiment has the optical fibercables 104 as shown in FIG. 2A. FIG. 6 shows a sectional view of thereflection type liquid crystal panel 504 of the present embodiment.Reference numeral 601 denotes a substrate. Reference numerals 602 and603 are driver TFTs. Reference numerals 604, 605, 606, and 607 denote apixel TFT, a reflection electrode, liquid crystal, and a countersubstrate, respectively. Dots 608 are formed on the counter substrate607.

The optical fiber cables 104 are positioned so as to emit light takeninto the counter substrate. Incident light entered into the opticalfiber cables enters the counter substrate 607, traveling through thecounter substrate 607, and then enters the liquid crystal 606. It is tobe noted that the dots 608 are formed on the upper surface of thecounter substrate 607 to allow incident light on the liquid crystal byeliminating the requirement for the total internal reflections of lighttraveling through the substrate at the interface.

[Embodiment 2]

The present embodiment is a case where the structure of the reflectiontype liquid crystal panel is modified in the notebook-sized PC describedin Embodiment 1.

Reference is made to FIG. 7, which shows a sectional view of thereflection type liquid crystal panel. Reference numeral 701 denotes asubstrate. Reference numerals 702 and 703 are driver TFTs. Referencenumerals 704, 705, 706, 707, and 708 denote a pixel TFT, a reflectionelectrode, liquid crystal, a counter substrate, and a light guide plate,respectively. Dots 709 are formed on the light guide plate 708.

In the present embodiment, again, light taken in the optical fibercables 104 enters the light guide plate 708, traveling through the lightguide plate 708, and then enters the liquid crystal 706.

[Embodiment 3]

The present embodiment is a case where the optical fiber cables aremodified which form the optical fiber array used in the liquid crystalpanel described in Embodiment 1 or Embodiment 2 as means for solving theabove-mentioned problem.

The optical fiber array of the present embodiment is an aggregate of aplurality of optical fiber cables as shown in FIG. 8. Each of theoptical fiber cables 801 is a bundle of a plurality of optical fibers802. A microlens array 803 is positioned at an aperture of each opticalfiber cable 801 for taking in the optical fibers. A coating 804 isformed of a resin or the like.

FIG. 9 illustrates the function of a microlens 803-1 forming themicrolens array 803 of the present embodiment. The microlens array 803is an aggregate of a plurality of microlenses 803-1. FIG. 9 shows onemicrolens 803-1 for conveniences' sake. The size of the microlens 803-1substantially equals to that of the clad of the optical fiber 802. Themicrolens 803-1 is positioned such that incident light on the microlens803-1 travels into the core of the optical fiber 802. Of course, theangle of incidence of light into the core of the optical fiber 802 isrequired to be set so as to cause total internal reflection. Thestructure of the present embodiment makes it possible to condense intothe core the incident light on the clad of the optical fiber, whichresults in obtaining large amount of light even with a small area.

FIG. 10 schematically shows the positioning of the microlenses 803-1correspondingly to the optical fibers 802 forming the optical fibercable 801. It is to be noted that, in practice, in an optical fibercable, the optical fibers 802 and the corresponding microlenses 803-1thereto are of course disposed three-dimensionally.

[Embodiment 4]

The present embodiment is a case where the optical fiber cables aremodified which form the optical fiber array used in the notebook-sizedPC described in Embodiment 1 or Embodiment 2.

Reference is made to FIG. 11. The optical fiber array of the presentembodiment is an aggregate of a plurality of optical fiber cables 1101as shown in FIG. 11. Each of the optical fiber cables 1101 is a bundleof a plurality of optical fibers 1102. A microlens array 1103 ispositioned at an aperture of each optical fiber cable 1101 for taking inthe optical fibers. A coating 1104 is formed of a resin or the like. Areinforcing material 1105 is formed of a resin or the like.

FIG. 12 shows a microlens 1103-1 forming the microlens array 1103 of thepresent embodiment. The microlens array 1103 is an aggregate of aplurality of microlenses 1103-1. FIG. 12 shows one microlens 1103-1 forconveniences' sake. The size of the microlens 1103-1 is larger than thatof the clad of the optical fiber 1102. The microlens 1103-1 ispositioned such that incident light on the microlens 1103-1 travels intothe core of the optical fiber 1102. Of course, the angle of incidence oflight into the core of the optical fiber 1102 is required to be set soas to cause total internal reflection. The structure of the presentembodiment makes it possible to condense into the core the incidentlight on the microlens 1103-1, which results in obtaining large amountof light.

[Embodiment 5]

In the present embodiment, a notebook-sized PC is described having meansfor solving the above-mentioned problem or a plurality of the opticalfiber arrays described in Embodiments 1–4.

FIG. 13 is a schematic structural view of a reflection typesemiconductor display device using a reflection type liquid crystalpanel according to the present invention. Reference numerals 1301 and1302 denote a main body and a reflection type liquid crystal panel,respectively. An optical fiber array 1303 has a plurality of opticalfiber cables 1304. Though, in the present embodiment, four optical fiberarrays 1303 are used, but the number thereof may be more or less thanfour.

[Embodiment 6]

The present embodiment is a case where the structure of the reflectiontype liquid crystal panel described in the above embodiments furtheruses a front light as an auxiliary light source.

FIG. 14 shows a sectional view of the reflection type liquid crystalpanel of the present embodiment. Reference numeral 1401 denotes asubstrate. Reference numerals 1402 and 1403 denote driver TFTs.Reference numerals 1404, 1405, and 1406 denote a pixel TFT, a reflectionelectrode, and liquid crystal, respectively. A counter substrate 1407 issimilar to the counter substrate shown in FIG. 3. Reference numeral 1408denotes an optical fiber cable. A front light 1409 is formed of aplurality of LEDs. Alternatively, the front light 1409 may be afluorescent lamp.

FIG. 15 shows LEDs forming the front light used in the presentembodiment. LEDs for emitting R (red), G (green), and B (blue) light areintegrally formed on a resin substrate to be used as a white lightsource.

In the present embodiment, in the case where auxiliary light from theoptical fibers is not sufficient, the front light is lighted, and thus,the front light is normally set non-operational.

[Embodiment 7]

The semiconductor device using the reflective type liquid crystal panelprovided with the auxiliary light source as the optical fiber arrayaccording to the present invention have various applications. In thepresent embodiment, such a semiconductor device will be described.

Semiconductor devices of this type include a video camera, a stillcamera, a car navigation system, a personal computer, and a portableinformation terminal (such as a mobile computer and a cellulartelephone), examples of which are shown in FIGS. 16A to 16C and FIGS.17A to 17E.

FIG. 16A shows a cellular telephone formed of a main body 1601, a voiceoutput portion 1602, a voice input portion 1603, a reflection typeliquid crystal panel 1604, an optical fiber array 1605, a control switch1606, and an antenna 1607.

FIG. 16B shows a video camera formed of a main body 1608, a reflectiontype liquid crystal panel 1609, an optical fiber array 1610, a voiceinput portion 1611, a control switch 1612, a battery 1613, and an imagereception portion 1614.

FIG. 16C shows a mobile computer formed of a main body 1615, areflection type liquid crystal panel 1616, an optical fiber array 1617,a camera portion 1618, an image reception portion 1619, and a controlswitch 1620.

FIG. 17A shows a personal computer formed of a main body 2001, an imageinput portion 2002, a reflection type liquid crystal panel 2003, akeyboard 2004, and an optical fiber array 2005.

FIG. 17B shows a goggles type display formed of a main body 2101, areflection type liquid crystal panel 2102, an arm portion 2103, and anoptical fiber array 2104.

FIG. 17C shows a player using a recording medium with a program recordedtherein (hereinafter referred to as a recording medium) and formed of amain body 2201, a reflection type liquid crystal panel 2202, a speakerportion 2203, a recording medium 2204, a control switch 2205, and anoptical fiber array 2206. It is to be noted that, with this device,listening to music, watching movies, playing games, and enjoyingInternet can be done with a DVD (digital versatile disc), a CD, or thelike used as the recording medium.

FIG. 17D shows a digital camera formed of a main body 2301, a reflectiontype liquid crystal panel 2302, a viewfinder 2303, a control switch2304, an optical fiber array 2305, and an image reception portion (notshown).

FIG. 17E shows a portable electronic book formed of a main body 2401, areflection type liquid crystal panels 2402 and 2403, a recording medium2404, a control switch 2405, an antenna 2406, and an optical fiber array2407.

According to a reflection type semiconductor display device of thepresent invention, light other than incident light on a liquid crystalpanel can be taken in to be an auxiliary light source using opticalfibers, and thus, display of high quality level can be made even indoorsor in a place where light is faint.

Further, by combining the semiconductor display device with a frontlight, insufficient amount of light can be supplemented with the frontlight.

1. A display device comprising: a reflection type liquid crystal displaypanel comprising: a light guide plate having a first surface, a secondsurface and a third surface; a substrate having a fourth surface facingto the second surface; and a liquid crystal between the second surfaceand the fourth surface; and an optical fiber having a first end and asecond end, wherein the first end faces to the first surface, andwherein the third surface and the second end take in external light. 2.The display device according to claim 1, wherein the display panelfurther comprises a thin film transistor over the fourth surface.
 3. Thedisplay device according to claim 2, wherein the display panel furthercomprises a reflection electrode electrically connected to the thin filmtransistor.
 4. A electronic apparatus comprising the display deviceaccording to claim 1, wherein the electronic apparatus is one selectedfrom the group consisting of a cellular telephone, a video camera, amobile computer, a personal computer, a goggles type display, a playerusing a recording medium with a program recorded therein, a digitalcamera, and a portable electronic book.
 5. The display device accordingto claim 1, wherein the light guide plate is a counter substrate.
 6. Adisplay device comprising: a reflection type liquid crystal displaypanel comprising: a light guide plate having a first surface, a secondsurface and a third surface; a substrate having a fourth surface facingto the second surface; and a liquid crystal between the second surfaceand the fourth surface; a microlens; and an optical fiber having a firstend and a second end, wherein the first end faces to the first surface,and wherein the second end faces to the microlens, and wherein the thirdsurface and the second end take in external light.
 7. The display deviceaccording to claim 6, wherein the display panel further comprises a thinfilm transistor over the fourth surface.
 8. The display device accordingto claim 7, wherein the display panel further comprises a reflectionelectrode electrically connected to the thin film transistor.
 9. Aelectronic apparatus comprising the display device according to claim 6,wherein the electronic apparatus is one selected from the groupconsisting of a cellular telephone, a video camera, a mobile computer, apersonal computer, a goggles type display, a player using a recordingmedium with a program recorded therein, a digital camera, and a portableelectronic book.
 10. The display device according to claim 6, whereinthe light guide plate is a counter substrate.
 11. A display devicecomprising: a reflection type liquid crystal display panel comprising: alight guide plate having a first surface, a second surface and a thirdsurface; a substrate having a fourth surface facing to the secondsurface; and a liquid crystal between the second surface and the fourthsurface; an optical fiber having a first end and a second end; and afront light disposed adjacent to the first surface, wherein the firstend faces to the first surface, and wherein the third surface and thesecond end take in external light.
 12. The display device according toclaim 11, wherein the display panel further comprises a thin filmtransistor over the fourth surface.
 13. The display device according toclaim 12, wherein the display panel further comprises a reflectionelectrode electrically connected to the thin film transistor.
 14. Aelectronic apparatus comprising the display device according to claim11, wherein the electronic apparatus is one selected from the groupconsisting of a cellular telephone, a video camera, a mobile computer, apersonal computer, a goggles type display, a player using a recordingmedium with a program recorded therein, a digital camera, and a portableelectronic book.
 15. The display device according to claim 11, whereinthe light guide plate is a counter substrate.
 16. A display devicecomprising: a reflection type liquid crystal display panel comprising: alight guide plate having a first surface, a second surface and a thirdsurface; a substrate having a fourth surface facing to the secondsurface; and a liquid crystal between the second surface and the fourthsurface; an optical fiber having a first end and a second end, and afront light disposed adjacent to the first surface, wherein the firstend faces to the first surface, wherein the front light comprises aplurality of LEDs, wherein the plurality of LEDs comprises an LED foremitting red light, an LED for emitting green light, and an LED foremitting blue light, and wherein the third surface and the second endtake in external light.
 17. The display device according to claim 16,wherein the display panel further comprises a thin film transistor overthe fourth surface.
 18. The display device according to claim 17,wherein the display panel further comprises a reflection electrodeelectrically connected to the thin film transistor.
 19. A electronicapparatus comprising the display device according to claim 16, whereinthe electronic apparatus is one selected from the group consisting of acellular telephone, a video camera, a mobile computer, a personalcomputer, a goggles type display, a player using a recording medium witha program recorded therein, a digital camera, and a portable electronicbook.
 20. The display device according to claim 16, wherein the lightguide plate is a counter substrate.
 21. A display device comprising: areflection type liquid crystal display panel comprising: a light guideplate having a first surface, a second surface and a third surface; asubstrate having a fourth surface facing to the second surface; and aliquid crystal between the second surface and the fourth surface; amicrolens; an optical fiber having a first end and a second end, and afront light disposed adjacent to the first surface, wherein the firstend faces to the first surface, wherein the second end faces to themicrolens, and wherein the third surface and the second end take inexternal light.
 22. The display device according to claim 21, whereinthe display panel further comprises a thin film transistor over thefourth surface.
 23. The display device according to claim 22, whereinthe display panel further comprises a reflection electrode electricallyconnected to the thin film transistor.
 24. A electronic apparatuscomprising the display device according to claim 21, wherein theelectronic apparatus is one selected from the group consisting of acellular telephone, a video camera, a mobile computer, a personalcomputer, a goggles type display, a player using a recording medium witha program recorded therein, a digital camera, and a portable electronicbook.
 25. The display device according to claim 21, wherein the lightguide plate is a counter substrate.